U.S. patent number 4,547,350 [Application Number 06/465,051] was granted by the patent office on 1985-10-15 for abatement of indoor pollutants.
Invention is credited to Hyman D. Gesser.
United States Patent |
4,547,350 |
Gesser |
October 15, 1985 |
Abatement of indoor pollutants
Abstract
Indoor pollutants such as formaldehyde can be removed from a
home reactive method consisting of a coating on a furnace filter in
a forced air heating system. The coating is a polymeric substance
with specific functional groups which react with the pollutant and
which in the case of formaldehyde or other aldehydes such as
acrolein or acetaldehyde would be a polymeric amine such as
polyethylenimine.
Inventors: |
Gesser; Hyman D. (MB R3P 0A7
Winnipeg, Manitoba, CA) |
Family
ID: |
23846310 |
Appl.
No.: |
06/465,051 |
Filed: |
February 9, 1983 |
Current U.S.
Class: |
423/210;
106/287.3; 423/245.1; 524/612; 525/540; 55/524 |
Current CPC
Class: |
A62D
3/30 (20130101); B01D 53/72 (20130101); A62D
2101/28 (20130101) |
Current International
Class: |
A62D
3/00 (20060101); B01D 53/46 (20060101); B01D
53/72 (20060101); B01D 047/00 (); C01B
021/00 () |
Field of
Search: |
;423/237,240,245S,21R
;524/555,606,608,612 ;106/287.3,287.29 ;525/540 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Valentine; Donald R.
Claims
What I claim as my invention is:
1. A method of reducing the indoor air concentration of
formaldehyde gas by coating a porous support filter with
polyethyleneimine and passing the indoor air through said support
filter.
2. A method according to claim 1 in which the polymer has
hydrazine, --(NH--NH.sub.2), functional groups.
3. A method according to claim 1 in which the polymer has primary
amine functional groups.
4. A method according to claim 1 in which the polymer is coated
onto a forced-air furnace filter and in which the operation of the
furnace fan circulates the indoor air through said coated
filter.
5. A method of reducing the indoor air concentration of
formaldehyde gas by incorporating into a paint for use on walls and
ceilings a water insoluble polymer which has free residual
hydrazine functional group remaining in the resultant dry
coating.
6. A method according to claim 5 in which the water insoluble
polymer has primary amine functional groups.
7. A method according to claim 5 in which the water insoluble
polymer has secondary amine functional groups.
8. A method of reducing the indoor air concentration of aldehydes
by allowing the air containing the aldehyde to come into contact
with polymers which have free residual hydrazine functional
groups.
9. A method according to claim 8 in which the polymer has free
residual primary amine functional groups.
10. A method according to claim 8 in which the polymer has free
residual secondary amine functional groups.
Description
BACKGROUND OF THE INVENTION
This invention is related to a simple, new and useful method
whereby some or all of a specific indoor pollutant can be
removed.
Conventional methods usually involve the adsorption of such
pollutants onto activated surfaces such as charcoal, silica gel,
alumina or other materials with large surface areas, (see R. E.
Goddard & J. A. Coles Canadian Pat. No. 625,216 and J. W.
Kasmark Jr., M. L. Dooley & A. H. Jones U.S. Pat. No.
4,227,904.
Another conventional method is to use a solution to react with the
specific gas, (see M. A. Kise, Canadian Pat. No. 643,062).
Such methods are usually non-specific and quite expensive to
produce and operate. In the case where aqueous solutions are used
the air becomes saturated with water and higher humidity levels
result. In the case of adsorption systems, the pollutant, usually
present in trace quantities, must compete with oxygen, nitrogen,
carbon dioxide and water in the air in order to be adsorbed to a
significant extent. The adsorption is also temperature dependent
and not always complete as far as the pollutant is concerned.
SUMMARY OF THE INVENTION
The present invention describes a simple and efficient method of
removing indoor pollutants by allowing them to react with a
polymeric substance which contains specific functional groups which
react with and form chemical bonds with the specific pollutant.
Different functional groups can be used for different pollutants.
Acidic carboxylic acid groups (--COOH) or sulfonic acid groups
(--SO.sub.3 H) can remove basic gases such as ammonia, or amines,
whereas basic groups such as amines can remove acidic gases such as
hydrogen halides.
Since the polymer is non-volatile and of high molecular weight the
product of the reaction between the pollutant and the
functionalized polymer is a solid and the result is that the
pollutant is removed from the air. The polymer, which can be coated
onto an air filter, does not contribute gases to the air nor is its
reactivity impaired by the presence of other gases. The use of two
coated filters in series, each treated with different
functionalized polymers could be used to remove different
pollutants.
DESCRIPTION OF THE PREFERRED EMBODIMENT
I have shown that a typical pollutant such as formaldehyde, which
may come from the decomposition of urea-formaldehyde foam
insulation or from the resin used in plywood or particle board, can
be removed by passing the air in the home through a fiber-glass
filter coated with a thin layer of a polymeric amine such as
polyethylenimine. Polyethylenimine is a water soluble polymer with
primary and secondary amine functional groups which react with
aldehydes as well as acidic gases.
Many homes use a forced air furnace as a means of supplying heat.
Such furnaces heat air which is circulated through the home by
means of a fan and which usually includes a filter to remove the
dust and particulate matter in the home. By coating such a filter
with the polymeric substance having suitable functional groups, it
is possible to remove the pollutant from the air as it is
circulated through the filter. Open cell polyurethane foam filters
can also be treated in this manner. The coated filter must be
replaced periodically, usually after about a month, more or less,
depending on the concentration of the pollutant in the air, the
size of the home, the size of the filter and the amount of
polymeric coating applied.
EXAMPLE 1
The air in a two storey home was analyzed during a three month
period and was shown to have formaldehyde levels of from 0.030 to
0.100 ppm due to the presence of urea-formaldehyde foam insulation.
A fiber-glass filter, 20".times.25".times.1" was coated with about
6 grams of polyethylenimine. This was done by spraying the filter
with about 150 mL of a 5% solution of the polymer in water and
allowing the filter to dry. The filter was then installed in the
furnace and the furnace fan run for one week. Analysis for
formaldehyde in the air then gave undetectable levels, i.e. less
than 0.001 ppm.
EXAMPLE 2
The air in a three storey split-level home was analyzed for
formaldehyde and was shown to have levels of from 0.050 to 0.140
ppm due to the presence of urea-formaldehyde foam insulation. A
fiber-glass filter 16".times.20".times.1" was treated with about
150 mL of a 5% solution of polyethylenimine and allowed to dry
leaving about 6.5 grams of polymer on the filter. The filter was
then installed in the furnace and the fan run. After one week the
levels of formaldehyde in the air were shown to be 0.008, 0.000,
0.000 and 0.000 ppm.
Other polymeric amines and some hydrazines are equally effective in
trapping aldehydes are polyvinylamine and polyethylene hydrazine
though many more can be prepare. It is also possible for the
functionalized polymer to be incorporated into a paint that is
applied to the walls and ceilings of a home. The pollutants can
diffuse through the outer layer of the paint and react with the
polymer forming chemical bonds thereby being removed from the air.
Aldehydes such as acrolein and acetaldehyde which are often present
in homes (see Indoor Pollutants, National Academy Press,
Washington, D.C. 1981) are also removed by polyethylenimine or the
above polymeric amines and hydrazines.
Since various modifications can be made in my invention as
hereinabove described, and many apparently widely different
embodiments of same made within the spirit and scope of the claims
without departing from such spirit and scope, it is intended that
all matter contained in the accompanying specification shall be
interpreted as illustrative only and not in a limiting sense.
* * * * *